U.S. Pat. No. 3,988,993 to Robert V. Brophy discloses a workpiece holding arrangement for use with automatic sewing machines. The workpiece holding arrangement consists of a book pallet having hinged leaves that are used to orient and locate several pieces of work which are to be sewn together. In this regard, each leaf of the book pallet contains one or more cavities that orient and accurately register the pieces of work that are to be sewn with respect to each other. The book pallet is connected to a high resolution positioning system which accurately positions the pieces of work relative to a reciprocating sewing needle.
Various other approaches have been used in orienting pieces of work that are to be registered with respect to each other and thereafter sewn by an automatic sewing machine. These approaches have included using a few pins strategically located within the pallet. Workpieces having the same pattern of holes therein are positioned over the pins. Still another approach has been to clamp the workpiece parts relative to each other after having aligned an edge of at least one piece with respect to an edge guide. Examples of these workpiece registration clamps are illustrated in U.S. Pat. No. 4,171,672 and U.S. Pat. No. 4,455,952.
The above arrangements for workpiece registration work well with material such as leather that is stiff enough to be manipulated relative to an edge, or positioned over pins or located within a cavity. A workpiece of a less stiff nature often requires a different approach. One such approach is disclosed in U.S. Pat. No. 4,449,463. The workpiece in this patented arrangement is placed between clamps which subject the workpiece to tension. This is a rather sophisticated arrangement for stretching the workpiece while registering it for sewing.